The farmers I've talked to told me that they never used 'em at all. They would just leave some in the outhouse and see what the city slickers did. Mostly they used pages from mail order catalogs, pieces of old newspaper or just paper, a piece of old rag, or leaves. (If you play with the catalog pages or pieces of newspaper while sittin' you can get them nice and soft, or at least somewhat pliable.)

By the way, these farmers were in several different regions of the US.

Dry cobs WERE burnt in winter to help extend the wood/coal supply.